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REPORT
OF
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OF
A SECTION OF THE RIVER DELAWARE,
ONE MILE BELOW CHESTER,
RICHMOND, ABOVE PHILADELPHIA.
TAKEN
BY ORDER OF THE COUNCILS.
BY DJIVID M'CLURE.
PUBIISHED BY OBDER OF COUNCIIS,
PHILADELPHM.-
PRINTED BY LYDIA R. BAILEY,
JiTO. 10, NORTH STREET.
1820.
f"\SS
REPORT
THE SURVEY
A SECTION OF THE RIVER DELAWARE.
THE duty which the Councils of Philadelphia have
assigned me, in the survey of a section of the river Dela-
ware, I have completed ; and it is my consolation to know,
and my privilege to assert, that I have not been faithless
in the discharge of the important trust committed to me.
As some accompanying remarks, with the draught of
the survey, may be expected, I will endeavour to give
them in as brief a detail as the nature of the case will
admit.
■■ To give a formal account, in this Report, of the methods
adopted in the prosecution of the survey, is deemed unne-
cessary ; and such information would only be interesting
to professional men. A history, however, of the plans
and methods pursued, has been laid before a few respect-
able and professional gentlemen ; by whom the correctness
thereof was duly investigated, and from whom those cer-
tificates, which are respectfully submitted to the Councils
at the close of this Report, were obtained.
It may not be amiss, however, to state, that every at-
tention was bestowed, to secure accuracy in the work,
and to render the survey as full and as perfect as possible.
A sloop and eight men were employed ; a liberal supply
of the best mathematical instruments procured ; and the
adoption of each plan, to suit the various cases in the
survey, was determined with much deliberation.
To secure accuracy in the work, no toils were spared.
In many places, especially where there was splatterdock,
water-grass, or soft mud, hardships and fatigues were
endured of no common nature. All the islands, sand-bars,
banks, whether natural or artificial, waterdock, commonly
called splatterdock, and the mud, to the low-water mark,
were faithfully taken. These various items are designated
on the chart by appropriate colours and suitable explana-
tions.
The necessity of exhibiting the low water mark, water-
dock edge, and banks, will at once be obvious, when we
consider the very different aspects which the river exhi-
bits in the different stages of the tide, particularly on long
flats. The coves on the Jersey side, below Gloucester,
and above Thompson's Point, present so different an ap-
pearance at high and low water, that they would scarcely
be taken for the same places.
The banks always exhibit the high water mark ; and
the edge of the mud or splatterdock, the low water mark.
All the houses that are conspicuous from the water are
also laid down, together with the wharves, wrecks of
vessels, including the frigates Augusta and Marlin, and
the buoys.
The direction of the current when in its strength, toge-
ther with its velocity, is marked in all those places where
it was deemed most important.
The compass exhibits the magnetic bearing of every
two points. The true north, with the angle, containing
the variation of the compass, two degrees forty-five mi-
nutes west, obtained by an observation taken for the oc-
casion, is marked in its proper place.
The ship channel and sloop channels are marked with
appropriate dotted lines. The depth of water is reduced,
and exhibited as taken at low water. The nature of the
bottom is carefully laid down, particularly where the
places are important. Large beds of muscles were found
in several places ; the most remarkable of which is that
on the flats between Woodbury dam and Mantua creek,
where they are so numerous that they seem to lie in con-
tact with each other.
The soundings taken on the shoals are numerous. The
ordinary and general soundings are exhibited at short
distances apart, and nearly at right angles across the
river.
The rise of the tide ahove low water was obtained by
means of a machine invented for the occasion, and which
was found admirably well calculated to answer the pur-
pose. It consisted of an upright piece of wood, notched
on each side like the teeth of a saw, into which a spring,
made fast to a floating board, takes hold. The notches
reversed, and boards appropriated to each, will accurately
exhibit the high and low water mark. A more full de-
scription is given in the Appendix.
The plan of the survey was drawn by means of an in-
vention which had been devised, not long previous, for
such purposes. By this instrument, great accuracy and
facility were attained in the draught. As this instrument
may be of essential service to surveyors and others in
plotting or draughting, it may be acceptable to such to
have a description of the same, with the pri\'ilege of a
free use thereof. (See Appendix.)
Considerable changes have taken place in the river,
since the last twelve or fifteen years. The island called
Gibbet island, formerly opposite the mouth of Schuylkill,
is entirely swept away : the fragments thereof seem to be
scattered down the river, and to have formed a consider-
able flat.
6
Bush island, formerly situated opposite Red Bank, has
shared the same fate : the ground on which it stood, and
for some distance below it, is considerably irregular and
uneven. At both ends of Chester island, the flats seem
to be increasing rapidly.
It is remarkable, that where a narrow channel is found
existing between an island and the main shore, the pas-
sage which opens up the river is shoaling, while the depth
of water increases down the channel. This is the case in
the passage between Shivers' island and the Jerseys, be-
tween Monnis island and the Jerseys, between Tinnicum
island and Pennsylvania, between Hog Island and Penn-
sylvania, between League island and Pennsylvania, be-
tween Wind Mill island and the Jerseys, between Petty's
island and the Jerseys. This circumstance seems imiver-
sal, and consequently admits of a philosophical investiga-
tion : it is deemed improper to enter upon it in this place.
A caution naturally presents itself to those who may
attempt passing through an inside channel from below,
without a knowledge of the same. The depth of water
which first presents itself may seem to intimate a channel
of more than sufficient depth ,• and the unwary may be led
on to a considerable distance, and almost to the upper end
of the channel, before they find themselves entrapped by
the shoal water.
A considerable change has also taken place between
Hog island and the Pennsylvania shore. Formerly, there
existed a considerable channel in that place ; and it is well
known, that during the revolutionary war a large British
ship passed up that channel, and attacked the fort in the
rear. At present, it can be forded at low water. The
soldiers often desert, and ford this channel, a little below
the fort, at low water.
Between Maiden island, particularly towards the north
end and the Pennsylvania side, a considerable change has
taken place.
That interesting part of our navigable waters, a little
below fort Mifflin, and known by the name of the Bar, is
subject to many changes. On taking the survey, it was
found that the lower buoy was not situated in the most
eligible place, owing to a change that had occurred dur-
ing the preceding two or three months. The lower buoy
is now removed considerably further up, so that the two
buoys are very near each other.
It was also found that a considerable shoal had formed
between the north end of Tinnicum and the Pennsylvania
shore, not exceeding two or three feet deep at low water,
on which several small vessels grounded while we were
surveying in that vicinity. A communication of the ex-
istence of this shoal was immediately made, and a rough
draft of the same forwarded to Joseph S. Lewis, Esq. chair-
man of the committee appointed to superintend the survey,
who reported the same to the proper authority. The buoys
were accordingly directed to be placed in a proper posi-
tion to designate the shoal, which has since been done.
This channel should be navigated with great caution,
on account of the irregularity of the ground, and the ra-
pid cross current which prevails during the flood tide.
The pier opposite fort Mifflin, formerly called Davis'
pier, now known by the name of Gaines' fort, was sunk
in the year 1777, in eighteen feet at low w^ater. To this
pier is attributed the formation of a long bar, which ex-
tends upwards of a mile down the river, and has proved
very injurious to our navigation.
The water seems to be undermining this pier very ra-
pidly; and, unless something be speedily done, it will
inevitably be thrown over into the river. In the year
1813, under the direction of the master warden of this
port, ten or twelve shallop loads of stone were thrown
around this pier, for the purpose of preserving its safety,
for which fears were then entertained.
8
At one of the corners towards the Jersey shore, there
are now, at low water, twenty-eight feet ', which is neces-
sarily from eight to ten feet below the foundation of the
pier. The soundings around the pier are exhibited in the
map.
Between the upper end of League island and the Penn-
sylvania shore, the bed of the channel is entirely exposed
at low water.
A considerable change has also taken place in the shoal
or bar which exists at the north end of Wind Mill island.
In the year 1777, a map was published by Mr. Scull, the
then city surveyor, in which this bar is represented to
be joined to the Jersey shore, at the point a little above
Cooper's ferry.
One proposition it is of importance to notice ; and that
is, that wherever the water is impeded in its motion, and
brought into a state of rest, or made to form what is call-
ed an eddy or counter current, there the sediment will
be deposited, and the place become shoal. This will be
the case where wharves, piers, or wrecks, exist: or where
a creek, sending its waters across the channel, checks the
velocity of the ebb tide on the shore below it ; or where
a creek, taking in the water on a flood, checks the velo-
city of the flood tide above. Hence it is, that at the mouth
of creeks we generally find flats.
It is remarkable that the Jersey shore has almost all
the flats. This may readily be accounted for, from the
circumstance of the soil being more fragile and sandy,
and less tenacious, than the Pennsylvania shore.
Any obstruction in the river, has a tendency to change
its direction ; and it is worthy of notice, that the current
on the ebb is so directed by the piers below the fort,
known by the name of the Boom piers, that it seems to
take an oblique course immediately between the two buoys
designating that part of the bar where the channel exists.
It is probable, that if an improvement be made on these
piers, by presenting an oblique side to the current, it
may have the happy eiFect of throwing a larger quantity
of water across the river, and thereby deepening the chan-
nel on the bar.
There is no doubt that the ebb tide gives the river its
particular character and direction, since much more water
passes down than up the river. It is on this account
chiefly, that so great an inequality exists between the
times of the ebbing and flowing of the tides ; the former
being about seven, the latter only five hours.
Bold banks are most exposed to the fury of a Adolent
current ; while flats, especially when covered with grass,
subdue the rage of a current almost into a calm.
The winds have a tendency not only to give the current
velocity, but also direction. Many artificial banks have
been prostrated, by a strong wind directing the current
against them. The banks of Hog island sometimes suffer
much from the north-east gales.
At the north-east end of this island, we found the pro-
prietors engaged in making a new bank, in the rear of
one which, in consequence of its being a little prominent,
had frequently been almost prostrated before the north-
east gales J and which was now deemed insufficient to stand
those gales any longer. The old bank was surveyed, and
the new one laid down.
It would be an important improvement to these banks,
to build them with a considerable declivity on the river
side, so that the violence of the waves and current would
thereby be much broken.
At the upper end of Hog island, in consequence of the
vast accumulation of ground recently made, the proprie-
tors were erecting banks that will enclose at least fifty
acres, and on the same place over which large sloops for-
merly sailed, at high water. As these new banks Vt ere
10
jiearly completed, they were surveyed, and no attention
paid to the old ones, as they will hereafter fall entirely
within the boundaries of the island, and may perhaps
soon be obliterated.
The small shoal that exists between Tinnicum island
and the Jersey shore, nearly opposite to Mr. Lodge's
dwelling, was formed from a pilot boat which was sunk
a number of years ago.
The remains of the British frigate Augusta, whose his-
tory is well known, lie at present in about six feet depth,
at low water. The sand and mud have accumulated around
her for some distance, and formed a considerable shoal,
in which she is nearly buried. While we were surveying
in the vicinity of that place, three or four eighteen pound-
ers were grappled up from the wreck, by men whose sub-
sistence depends on that business. The cannons are per-
fectly free from rust, and are supposed to be in as good
condition as they ever were, after having lain in the water
upwards of forty years.
More than ordinary attention was bestowed on that part
of the survey which is immediately within the vicinity of
the contemplated bridge. The direction of the current, its
tendency to produce an effect, its velocity in ebbing and
flowing, the depth and nature of the bottom, were taken
with scrupulous exactness. The ebbing and flowing of
the tides make first in this place, as is usually the case in
the shoaler channels.
The velocity of the current in this channel is much in-
ferior to that of the western channel ; and, as a vertical
section of the latter, in the narrowest place, is more than
three times as great as the former, it must of necessity
convey the great mass of water in the ebbing and flowing
of the tides.
The eastern channel has throughout a depth of twelve
feet at low water, and in the narrowest part has a breadth
11
of four hundred and fifty feet, commanding a depth of ten
feet at low water.
This channel may be navigated, at high water, by our
ships drawing fourteen feet. Our pilots are generally
ignorant of the nature of this channel ; and on extraordi-
nary occasions only would they be induced to prefer it,
especially as it terminates above that part of the city
where the shipping generally lies.
Sloops often use this channel to an advantage | and, in
contrary winds, and near high water, can tack more than
three-fourths of the distance from shore to shore. A ves-
sel coming up to Philadelphia, with the wind from the
west, and the tide ebbing, may pass up this channel, and
arrive at the city, when such arrival could not be effected
by the western channel. Similar advantages are afforded
to a vessel descending the river.
Vessels bound above the city from below, may take tliis
channel as the more direct course ; and, should there be
an ebb tide, they will have less current to encounter than
in the western channel. Vessels descending the river
will have similar advantages.
A strong westerly wind drives the great mass of ice
into this channel, and relieves the western side. A con-
trary wind produces a contrary effect. Each channel has
been used by turns, as they have been thus cleared of ice.
The water, on the ebb, coming out of Cooper's creek,
throws the current over near the flats on the south end of
Petty 's island, and has a direct tendency to check the water
from flowing freely down this eastern channel.
The ordinary rise of the tide is about five feet : but it
is very variable, on many accounts. A strong easterly
wind has been known to raise the tide three feet above
the ordinary height | while a strong westerly wind has
been known to depress it three feet below the ordinary
low water. A long drought will sensibly depress the tide^
while heavy rains will not fail to raise it.
12
The moon also has her influence on the tides ; and the
effect produced depends upon a combination of circum-
stances. The highest elevation, and lowest depression,
of tides, are produced, when, at the same juncture, there
occur the time of the equinox, the moon in conjunction
or opposition to the sun, and she near her perigee. A
reverse position in the heavens will produce a reverse
effect.
The tide rises most rapidly on the first of the flood. In
the short period of one hour and a half, the tide will be
more than one half up. Annexed is a table, exhibiting
the rise of the tide for every half hour, to the nearest
inch, the fractional parts being rejected :
The -whole rise
The rise for
of the tide.
each half hour.
ours.
ft-
in.
ft-
in.
oi
1
2
1
2
1
2
3
1
I
H
3
2
0
11
2
3
11
0
9
H
4
7
0
8
5
1
0
6
H
5
5
0
4
4
5
8
0
4i
5
10
0
2
5
5
11
0
1
It is very remarkable that the tide rises in the ratio of
ten inches for the first half hour, nine inches for the se-
cond, eight inches for the third, and so on, in an arith-
metical decrease, to unity. This simple ratio can be
easily remembered, and from it the proportional rise of
the tide may be readily calculated for any half hour, after
the manner illustrated in the next page.
13
The following table exhibits the fall of the tide for
every half hour^ to the nearest inch :
The -whole fall
of the tide.
The fall for
each half hour.
hours.
ft-
«72.
ft-
in.
oi
0
8
0
8
1
1
4
0
8
li
1
11
0
7
2
2
6
0
7
2i
3
0
0
6
3
3
6
0
6
^2
3
11
0
5
4
4
4
0
5
4*
4
8
0
4
5
5
0
0
4
5|
5
3
0
3
6
5
6
0
3
6i
5
8
0
2
7
5
9
0
1
As the whole fall of the tide requires much longer time
than the rise, it will necessarily be less rapid in falling
than in rising. There appears, however, a considerable
analogy in their ratios. The proportional fall of the tide
for any half hour required, may be found by assuming 14
for the first, 13 for the second, 12 for the third, and so on,
in a decreasing arithmetical progression, to unity: for
example, let it be required the proportional fall of the tide
for one hour and a half, that is for three half hours ; 14,
13, and 12, added, will be 39^ and the sum of 14, 13, and
12, &c. to unity, is 105; therefore, as 39 is to 105, is the
proportion required nearly one-third, which is agreeable
to the table.
14
From the above table, it will be apparent, that the tide,
in the short period of about two hours and one quarter,
will be half down.
The above observations were taken at a time when it
was calm, and the tide about an ordinary height. A
strong wind or freshet will necessarily affect the ratios
of the rising and falling of the tide herein exhibited ; yet,
notwithstanding, the proportions will nearly hold good
in all cases.
The effect of a freshet on the channel is twofold, — that-
arising from an increased velocity of water, and from an
increased quantity of sediment, which it invariably brings
down. The effect of ice is most to be dreaded, when there
are united with a freshet a high tide and strong winds.
The tide originates in the ocean, and is principally
the effect of the moon's attraction. The sun's attraction
has a partial effect, producing a change on the principal
effect.
No motion is produced in the waters in the middle of
the ocean, except a perpendicular one, equivalent to the
rise of the tide. Were the globe a mass of water, there
would be no horizontal motion occasioned by the tide.
Some writers, and of reputation too, have however in-
timated the contrary, and given us to understand, that
the whole ocean, under the influence of the tide, has a
horizontal motion. Dr. Young, in particular, mentions,
that " the tide, entering the Atlantic, appears to advance
northwards at the rate of five hundred miles an hour,
corresponding to a depth of about three miles, so as to
reach Sierra Leone at the eighth hour after the moon's
southing."
Dr. Young and others surely do not mean what they
appear to intimate. We lament, to say the least of it,
that their expressions are unfortunate, and too much cal-
culated to lead inquiring minds astray.
15
The horizontal motion of the sea, near the land, and
up hays and rivers, is not the immediate and primary ef^
feet of the moon or sun's influence ^ hut arises from the
circumstance, that the abutments (to use a figure) of the
great arch of the elevated water being too weak near the
shore, by reason of shoalness, to sustain the pressure, a
horizontal motion is produced, the eifect of which is felt
at great distances, up channels, bays, and rivers.
The momentum which the waters thus receive, is not
an absolute motion of the whole mass of watery but some-
thing like the impulses of the air, or like that motion
which is produced on throwing a stone in the water.
The high water at Cape May is about six hours reach-
ing Philadelphia, a distance of about a hundred and twenty
miles. Now, if this tide be the effect of an absolute hori-
zontal motion of the whole mass of water, then the tide
must move at the rate of twenty miles per hour, which far
exceeds the true velocity. It is near low water at Phila-
delphia, when it is high water at Cape May,- and vice
versa.
The tide has been very justly compared to a wave, the
top of which is at the Cape, and the bottom near Phila-
delphia. A vessel leaving Cape May in the early flood,
and arriving in Philadelphia within eleven hours, will
bring the flood tide the whole distance with her. But, in
descending the river, the tide will be anticipated one hour
in about the distance of every twenty miles.
The momentum, as explained above, which the tide has
on entering a river, is the whole body of water multiplied
into its celerity ; and if this momentum be not powerfully
diminished by friction, it will have a tendency to press
with considerable force as the river narrows and shoals,
thereby making up in velocity what it loses in space; the
effect of which will be, that the water will have sufficient
power to ascend the river considerably above its natural
level.
16
If Philadelphia be supposed to be a hundred feet above
the level of Cape May, the angle of ascent will in that
case not exceed half a minute of a degree, which very
gradual declivity the tide would not require much force
to surmount. We can scarcely suppose that the high water
mark at Philadelphia, so many miles from the ocean, is
not above the level of the high water mark at Cape May.
Were fifteen or twenty miles faithfully levelled, it would
fully establish the truth.
The more irregular the river is, and the more shoals
and islands in it, the greater will be the friction, and
consequently the less will be the force of the water to
ascend above the level.
If a trough be made, and placed in a position a little
elevated, with the one end in water, it will be found, on
producing a wave, that the water will ascend in the trough,
and rise considerably above its level, especially if the
sides of the trough be converging to each other from the
water.
It is probable that a declivity of the river is an addi-
tional cause to that already stated, for the inequality in
the times of the ebbing and flowing of the tides.
A log, set afloat in the middle of the current, on the
first of the ebb, will never return on the flood to the same
place, unless it descend twenty miles, and have a current
equally strong on the flood. If the log descend twenty
miles, it will anticipate the flood one hour, and conse-
quently will only have six hours in descending ; and if
the current be equally strong on the flood, the log in re-
turning will gain one hour, whicli will make its whole
time on the flood six hours, equal to the time on the ebb,
and therefore it will be brought precisely back to the
place whence it started.
If the log descend more than twenty miles, it will, on
the flood, I'eturn and pass above the place left. For
example, if we suppose it to descend forty miles below
17
Philadelphia, it will anticipate the flood two hours, and
therefore will only he five hours in descending ; and the
flood, having the same velocity, will hring it back in five
hours, and gain on the flood two hours ; in which time,
at the same rate, it will ascend sixteen miles above Phila-
delphia, from which place it was supposed to start on the
first of the ebb.
It seems a paradox to say, that the farther down the
river the log descends on the ebb, the farther up the river
it will ascend on the flood : but the fact has been made
very obvious.
AVe cannot, however, reverse the proposition, and say,
that the least distance the log will descend on the ebb, the
farther it will be below the place on the close of the flood.
There must therefore be a point, to which, if the log de-
scend, it will, on the close of the flood, be the farthest
distance possible below the place left, supposing, as be-
fore, the strength of the ebb and flood tides to be equal.
To ascertain this point, the following solution is pro-
posed,' and, by its plainness, is accommodated to those
who may not be much versed in the mathematics :
n = number of minutes difference of tide in 1 mile, =
3 minutes.
a = number of minutes the tide ebbs.
6 = number of minutes the tide flows.
X = distance carried down by the ebb.
a — n X = time in descending with the ebb.
1/ = the distance brought up on the flood.
X : (h—nx : : ij : a y—n x y ^ rthe time coming
X Xup on the flood.
Again, b+n y= also the time coming up on the flood.
Therefore, a y — n x y
X
And y =bx
-2 nx
b+ny
iS
b X
Consequently, x is a maximum.
a — 2 11 X
The fluxion of which is x — h ax
a — 2 11 X I
2
fl2 X — 4 a % a? as'+4 -/i^ a:^ a? — & ax= 0
4 w^ x^ — 4 anx = b a — a^
x^ — a X b a — d^
11 4 ir
X^ — a X a^ b a
— I
I ^ 4i
a + 1
H =
11 4 11^ 4 11^
X ==
= — — -r— ^-j— =10.838966, the distance sought.
So that the distance sought will he 10 miles 14r6 yards,
and will be 6h. 27' 29" in descending. The log on the
flood will return 9 miles 281 yards in 5h. 27' 29", which
is 1 mile 1195 yards below the place left, the greatest
distance possible, supposing both tides of equal strength.
The tide falls considerably towards the close of the
flood, and before the current begins to run down in the
middle of the river. It was found, on repeated trials, to
vary from six to twelve inches in its fall, and to be from
thirty minutes to one hour and a half in falling. The wind
from the southward prolongs the time of its falling, and
produces the greatest fall ; but the wind from the north-
ward produces the contrary effect.
This circumstance induced a suspicion, that the water
towards the bottom of the river descended, while it was
running up on the top. Not that the sinking must neces-
sarily depend on the water descending tlie river ; for the
tide, like a wave, may continue to run up, and rise, until
its apex has passed, and then produce a consequent sink-
ing, without a particle of water descending the river.
19
However, to ascertain the truth, a long cylindrical
piece of wood was procured, and loaded at one end, by
putting lead into a cavity formed for the purpose, until it
was made to sink in a perpendicular position, so as to
leave only about three feet out of water.
Now it is evident, that if this pole be placed in the cur-
rent, it will show, by its inclination, whether the top or
bottom of the river has the greater velocity ; for, if the
rod incline forward, according to the direction of the cur-
rent, it is an evidence that the water towards the surface
has the greatest velocity ; but if it incline backward, it
shows that the swiftest current is towards the bottom : if
it retain a perpendicular position, the current in that case
must either have an equal velocity from the top to the
bottom, or have the least one near the middle, while to-
wards the surface and bottom the velocities must either
be equal, or so adjusted by different celerities, as to keep
the pole in that position.
In this way, several trials were made; and it was
found, that both on the ebb and flood tide, the pole in-
clined at the top up the river, indicating thereby that the
bottom had the greater velocity on the ebb, and the top
the greater on the flood. On the ebb, the pole, as an
evidence of this, moved faster than the boat which was
left to float down after it, but on the flood it was found to
move slower.
It was truly remarkable, that, near the close of the
flood tide, the pole first became stationary, and shortly
afterwards began to descend the river, while on the sur-
face every thing was drifting up. These facts fully esta-
blished the point which first induced the experiment to be
made.
To make a more complete investigation of the different
velocities of the river, from the surface to the bottom, the
following plan was pursued. A large boat was procured,
and anchoi'ed in the njiddle of the river, nearly opposite
20
Walnut street ; at the stern of which was fixed the trian-
gular instrument ABC, (See Fig. 1.) whose sides were
about four feet in length. The side B C was graduated in
degrees and quarters, about A as a centre, and numbered
from B to C. Through the centre A, a bolt was fixed,
by which the instrument was suspended, and over which
a line, fastened to a nine pound ball, W, was passed. To
this bolt also was suspended the weight R, by which the
side A B was brought into a perpendicular position, when
in use. The line to which the weight W was fastened,
was marked by loops, tied at every five feet apart.
Thus prepared, the velocity of the tide was taken on
the surface, in the usual way, for every fifteen minutes,
during the whole of the flood and ebb ; and also the an-
gles, which the string A W made with the perpendicular
line A R, taken from the graduated side B C, at the ob-
lique distance of every five feet from the surface of the
water to the bottom.
From these oblique distances and angles, the perpendi-
cular depths were calculated ; and from this depth the
corresponding angles were proportioned for every five
feet. To illustrate which, the following is an example :
5
10
15
20
25
30
35
40
45
50
55
60
65
8
12
16
20
23
26
29
31
33
34
35
36
37
5
9.8
14.4
18.8
23
27
30.6
34.3
37.7
41.5
45.1
48.5
51.9
8.
12
16
21
25
28
31
34
35
36
The first line exhibits the oblique depths of every five
feet ; the second, the angles which were found to corres-
pond to the same; the third, the perpendicular depth, cal-
culated for each angle and oblique depth ; and the fourth
is the angle under which the line A W will make with the
perpendicular line A R, corresponding to the nearest de-
gree, proportioned for every five feet perpendicular depth.
For example: to the perpendicular depth of 18.8 feet, the
corresponding degree is 20, and to 23 feet 23 degrees 5
21
therefore, 21 is the nearest proportional degree for a^er-
pendicular depth of 20 feet.
The following table is the result of an experiment on
the flood tide, taken on the 8th June, 1820, two days be-
fore the new moon. The first column shows the times at
which the observations were made ; the second, the velo-
city of the current at those times, exhibiting its rate per
hour, in statute miles and hundredths ; the remaining co-
lumns, the different angles, corresponding to every five
feet perpendicular depth, marked on the top :
Time
Bate of
current.
5
10
15
20
25
30
35
40
45
50
8
Slack
water.
8i
0.25
1
2
3
4
5
6
7
7
8
8
H
0.75
3
5
8
11
13
15
17
19
20
21
8|
1.15
5
8
11
14
18
23
28
29
29
29
9
1.87
9
14
20
27
33
37
41
44
46
48
H
2.17
11
16
22
29
37
45
50
54
56
57
9|
2.20
12
17
23
30
38
45
50
55
57
58
91
2.23
12
19
27
35
42
48
51
55
57
58
10
2.32
12
20
29
37
45
52
56
59
61
61
lOi
2.40
13
20
28
36
44
51
54
57
59
59
lOi
2.40
13
20
28
36
44
51
54
57
59
59
10|
2.37
13
20
28
36
44
50
53
56
57
57
11
2.37
13
20
28
36
44
49
51
53
55
55
Ui
2.27
12
17
23
29
37
45
50
52
54
54
Hi
2.25
10
15
21
27
33
38
41
43
45
45
111
1.78
8
12
16
21
25
28
31
34
35
36
12
1.60
6
9
12
15
17
20
23
25
26
27
12i
1.15
3
5
7
9
10
11
12
13
14
14
12§
0.75
1
2
2
2
3
3
3
4
4
4
12|
0.32
0
0
0
0
0
0
0
0
0
0
1
Slack
water.
0
0
1
1
2
2
3
3
4
5
At 1 o'clock, it was slack water; at which time, the angles were
made down the river.
22
The following was taken on the ebb tide, the same day :
Time.
current.
5
10
15
20
25
30
35
40
45
9
50
10
H
0.42
1
2
3
4
5
6
7
8
H
1.12
3
5
7
9
11
13
15
17
19
21
If
1.50
6
9
12
15
19
23
27
31
34
37
2
1.60
7
11
15
20
25
31
37
42
46
48
H
2.0O
10
16
23
30
38
45
48
50
52
53
n
2.32
12
20
29
39
49
57
62
64
65
66
n
2.37
12
20
29
39
49
57
62
64
65
66
3
2.25
13
21
30
40
51
58
63
65
67
68
H
2.25
13
21
30
40
51
58
63
65
67
68
H
2.25
13
21
30
40
51
58
63
65
67
68
3|
2.37
14
22
31
41
51
58
63
65
67
68
4
2.32
13
22
31
40
49
56
60
62
64
65
4i
2.30
13
22
31
40
48
54
57
59
61
62
H
2.30
13
22
31
40
48
54
57
59
60
61
4|
2.26
13
22
31
39
47
52
56
58
59
60
5
2.25
13
21
30
38
45
49
54
57
58
59
H
2.25
12
20
29
37
45
49
53
55
57
58
sh
2.25
12
20
29
37
45
49
53
55
56
57
51
2.00
12
20
29
37
45
49
53
55
56
57
6
2.00
11
19
27
36
45
49
52
53
54
55
6*
2.00
11
18
27
36
45
49
52
53
54
55
6^
2.00
10
17
26
35
45
49
51
53
54
55
6|
2.00
10
16
24
32
40
47
49
50
51
51
7
1.75
8
14
20
25
28
31
36
38
41
43
7"*
1.00
4
6
8
9
10
11
11
12
12
13
74
0.27
0
0
1
1
1
2
2
2
3
3
7 35'
Slack
water.
0
0
0
0
0
0
0
0
0
0
7#
0.50
2
3
4
5
6
6
7
7
8
8
At 7 o'clock and 45 minutes, it was flood tide.
From these tables, tlie velocity of the water may be
calculated for the depth of every five feet, on the princi-
ples of the inclined plane, in which we have the size and
density of the ball, and the angle under which it was kept
in equilibrio. The rope by which the ball was suspended
was one-sixth of an inch in diameter, for which an allow-
ance must be made. These tables will be found of essen-
tial service, in pursuing various investigations that may
be made on the tides.
23
Another method, to obtain the different velocities of the
current, was devised, equally accurate, while, at the same
time, it was simple, and less incumbered with calculations.
It nearly agrees with the calculations resulting from the
first experiment.
Let A (Fig. 2.) represent the stern of the large boat,
which was anchored near the same place where the first
experiment was madej B, a board about four feet in length,
sharpened at both ends; A B, the log line, fastened to the
end of the board, by which the different velocities of the
tide were obtained ; D, a nine pound ball, immediately
over which was fixed a cross-square to hold the water,
the pieces of which were made of thin stuff, about one foot
long and four inches broad, and the upper edges bevelled,
so as to lessen the resistance while drawing it in. The
line C D, by which tlie ball was suspended, had loops
fastened at every ten feet, so that, by means of a hole in
the middle of the board B C, and a stick to pass through
those loops and rest on the board, the ball was readily
suspended at every ten feet from the surface of the w^ater
to the bottom.
A loop was also fixed immediately over the cross-square,
so that the ball, when suspended by it, was not more than
eight or ten inches under water. In this last position,
the rate of the surface of the water was taken ; and, by
lowering the ball from one loop to another, the velocity of
the current was obtained for the depth of every ten feet.
An allowance must be made for the resistance of the board,
and of the rope, which was one-sixth of an inch in dia-
meter.
It is evident, that when the velocity exhibited in the ta-
bles, at any depth, is greater than that on the surface,
the true velocity will be something more. But when less,
the true velocity will be less. As the ball and cross-square
present a large proportion of resisting surface, the true
velocities cannot differ much from the tables.
24
The following table is the result of an experiment,
taken on the 1st of July, 1820, one day before the last
quarter of the moon, and on the ebb tide, for every half
hour. The first column shows the time ; the second, the
rate on the surface ; and the remaining columns, the rate
for every ten feet depth, all of which are given in statute
miles and hundredths :
Time.
Rate of
current.
10
20
30
40
50
6|
Slack
water.
7i
0.60
0.80
1.00
1.05
1.20
1.20
7i
1.25
1.50
1.75
1.85
1.95
1.95
8i
2.12
2.25
2.40
2.50
2.40
2.30
8|
2.65
2.50
2.40
2.30
2.40
2.45
H
2.50
2.48
2.46
2.45
2.45
2.45 '
9|
2.62
2.55
2.50
2.45
2.35
2.30
lOi
2.40
2.40
2.42
2.42
2.35
2.30
lOf
2.25
2.35
2.45
2.40
2.36
2.32
Hi
2.25
2.40
2.52
2.39
2.28
2.15
111
2.12
2.20
2.36
2.34
2.31
2.25
I2i
2.12
2.14
2.15
2.17
2.09
2.08
121
2.00
2.15
2.18
2.20
2.14
2.09
H
1.87
1.87
1.90
2.00
1.82
1.75
2
0.85
0.88
0.92
1.05
0.83
0.78
Slack
water.
On inspecting the above table, it will be found, that, at
6 o'clock and 45 minutes, it was slack water on the sur-
face, at which time the velocities for the different depths
were not taken. At the second hour, the tide has the
greatest velocity; and, after diminishing its velocity,
during the third hour, it again increases for a short time.
This occurred in both experiments, which may be seen
on comparing the tables.
At 71, 7|, and 8|, the velocity towards the bottom was
the greatest ; at 8|, 9^, and 9|, the velocity towards the
top was the greatest j and during the remaining times,
the middle of the liver had the greatest velocity. It has
25
been observed, that the top of the pole, on the few trials
that were made on the ebb, uniformly pointed up the
river. It will be found, on inspecting the table, that a
pole about thirty feet long will always retain that posi-
tion, except about one hour and a half from the second
hour of the ebb, about which time a trial with the pole
had been omitted.
The following was taken on the flood, the same day :
Time
Rate of
current
10
20
30
40
50
n
1.43
1.40
1.35
1.28
1.25
1.25
3
2.89
2.86
2.80
2.75
2.70
2.70
3g
2.87
3.00
2.82
2.76
2.62
2.60
4
3.00
2.95
2.85
2.85
2.85
2.80
4i
3.00
2.85
2.82
2.80
2.76
2.75
5
2.75
2.68
2.50
2.48
2.42
2.40
5§
2.37
2.29
2.27
2.25
2.20
2.20
6
1.77
1.90
1.95
1.72
1.67
1.60
6i
1.50
1.40
1.35
1.32
1.28
1.25
6|
1.00
0.85
0.80
0.78
0.75
0.55
7
0.75
0.62
0.35
0.12
Stat'y
Des'g-.
0.15
H
Slack
water
0.10
0.23
0.28
0.35
0.37
On inspecting the above table, it will be found, that
at the second hour, the tide has its greatest velocity,
and that almost uniformly the surface of the water has
the greatest velocity. Towards the close of the flood,
the velocities were taken for every quarter of an hour,
as it was then important to ascertain minutely every
change.
At 7 o'clock, at the depth of forty feet, the board was
stationary ; and, at the depth of fifty feet, the tide was
descending the river. At 71, it was slack on the top,
while the board descended the river, with the different
velocities annexed to the different depths.
4
26
It is probable that the tide begins to run down at the
bottom at least half an hour before the top. At 7 o'clock,
at the depth of fifty feet, the board was drawn down the
river, when at the same time the top had the velocity of
three quarters of a mile per hour up the river: from which
it will be evident, that the current towards the bottom, at
that time, must have had a considerable velocity, such as
to communicate to the ball and cross-square a sufficient
force to overcome the resistance near the surface.
The velocity with which the board left the boat, for
the first twenty or thirty feet after the ball had been
lowered forty or fifty feet, was ve^'y remarkable. As
nearly as could be estimated, it moved at the rate of
from fifteen to twenty miles per hour. A considerable
length of stray line (as it is termed) was allowed the
board, so that it should have full time to acquire the
proper and uniform velocity of the current. From these
experiments, many results, of practical importance, may
be deduced. It is apparent, from the table, that a small
vessel will drift faster on the flood than a large one, and
slower on the ebb.
From the first experiment, it appears, that the velocity
of the whole ebb was sufficient to have drifted the dis-
tance of 12.47 miles, supposing no anticipation of the
tide down the river, and on the flood 8.15 miles, which
makes the distance on the ebb in a greater proportion
to the flood than their periods of ebbing and flowing,
seven and five hours. In the second experiment, the
reverse of this is found to be the case. This difference
arises either from the irregularity of the sun and moon's
influence, or from the effects of wind or freshets, whicli
increase the velocity, and prolong the ebb tides. How-
ever, in forming an estimate, we have reason to con-
clude tliat their mean velocities will be about equal, and
their distances in proportion to their times of ebbing
. 2T
and flowing, agreeably to the supposition made in the
solution of the proposition respecting tlie descent of the
log.
From this proposition, and the velocities of the tides
thus considered, it may be inferred that the whole of the
upper water brought down the river during twelve hours,
would be sufficient to fill a space included in a section of
the river 1 mile 1195 yards in length.
The contents of this space may be found, by taking
the sum of all the soundings exhibited in the draught,
in one line across the river, and dividing the same by
the number of soundings, for the mean depth : this being-
multiplied by the breadth of the river, will give the area
of a vertical section in that place. A number of these
sections near Philadelphia were calculated, and the mean
was found to contain 51,000 superficial feet, which, mul-
tiplied by 1 mile 1195 yards, or, which is nearly equal
to the same, by 9,000 feet, will give 459,000,000, the
contents of the space required, in solid feet. Each solid
foot contains about 7i gallons, from which the contents
are found to be 3,442,000,000 gallons, equal to 54,000,000
hogsheads.
The greatest velocity of the current is generally about
the deepest part of the river. In shoal water, it is greatly
diminished by the friction of the bottom, particularly
when it is rough and uneven.
Those places have an increased velocity on the ebb,
where t!ie vertical sections are less than those farther
up the river; but where the vertical sections are greater,
there will be a diminution of velocity, except there be a
creek or river some short distance above, whose waters
will sufiice to fill the proportional increase of that sec-
tion.
28
The following list exhibits some of the most important
sections in the survey : —
feet.
From Richmond to Petty's island, 2,550 feet,
mean depth 14 feet, area of section - 35,700
In the same line from Petty's island to Jersey,
1,500 feet, mean depth 14.3 feet, area of
section - - - - 21,450
Whole area, from Richmond to Jersey, - 57,150
From Pennsylvania to Jersey, crossing to the
south of Petty's island, 4,500 feet, mean depth
12.5 feet, area of section - - 56,250
From Cooper's Point to Nagle's vi^harf, at the
mouth of Cohocksink creek, 3,000 feet, mean
depth 20 feet, area of section - - 60,000
In the eastern channel, the smallest section is
from a point a little above Cooper's ferry to
the bar, 1,300 feet, mean depth 7 feet, area
of section - - - - 9,100
From Walnut street wharf to the island, 900
feet, mean depth 30.5 feet, area of section - 27,450
In the same line from the island to Jersey, 2,100
feet, mean depth 9 feet, area of section - 18,900
Whole area, from Walnut street to Jersey, - 46,350
The section in the eastern channel, from the
south end of the island to Jersey, 1,680 feet,
mean depth 13.3 feet, area of section - 22,344
From the Pennsylvania to the Jersey shore,
about half a mile below Kaign's Point, 3,300
feet, mean depth 15.2 feet, area of section - 50,160
From the wharf at Greenwich Point to Jersey,
2,250 feet, mean depth 21 feet, area of sec-
tion - - . . . 47,250
29
feet.
From a point about half a mile below the wind-
mill, in the Cove, to League island, 4,500
feet, mean depth 17.5 feet, area of section - 78,750
From the south end of League island to Jersey,
4,200 feet, mean depth 14.8 feet, area of sec-
tion - . - . . 62,160
From Fort Mifflin to Jersey, 5,100 feet, mean
depth 13.8 feet, area of section - - 70,380
From Mud island, across the channel on the
bar, to Jersey, 4,800 feet, mean depth 15.8
feet, area of section - _ - 75,840
From the Jersey to the Pennsylvania shore, in
a line with the north end of Maiden island,
4,800 feet, mean depth 14.4 feet, area of sec-
tion . . - . - 69,120
From the Jersey to the Pennsylvania shore, in
a line with the south end of Tinnicum island,
5,700 feet, mean depth 16.4 feet, area of sec-
tion - _ - _ . 93,480
From Chester to Jersey, 6,600 feet, mean depth
17.6 feet, area of section - - 116,160
From the north end of Schiver's island to the
Pennsylvania shore, 5,400 feet, mean depth
24.6 feet, area of section - - 132,840
From the nortli end of Schiver's island to .Jer-
sey, 1,500 feet, mean depth 4 feet, area of
section . - - - > 6^000
Area of whole section, from the Jersey to the
Pennsylvania shore, - - - 138,840
The narrowest part of the river, between Windmill
island and Pennsylvania, is the line drawn at right an-
gles to Smith's wharf on the island. The section across
30
from Walnut street will be nearly the smallest in this part
of the river J but in the eastern channel, the smallest sec-
tion is a little above Cooper's ferry to the bar, which is
less than a third of the smallest section in the western
channel, as has been stated in a former part of the Report.
The section in the eastern channel, opposite Walnut street,
is more than double the smallest section in that channel.
From a view of the foregoing list of sections, it is evi-
dent that at Walnut street, and at Greenwich Point, the
velocity of the current must be greatly increased ,* and in
the Cove below Gloucester and the Windmill, much de-
creased. The water flowing out of Timber creek is much
less than the proportional increase of that section.
The sections, upon the whole, are gradually increasing
down the river. The last section in the list contains np-
wards of double the area of the first. Their distance
apart is about twenty -tbree miles. In this distance, there
are a number of creeks entering the river ; to accommo-
date the waters of which, an increase in the bed of the
river is necessary ; otlierwise, a considerable increase in
the velocity of the current would be the result.
On the Pennsylvania side, are Cohocksink and Hol-
lander's creeks, Schuylkill river, Derby, Crum, Ridley,
and Chester, creeks. On the Jersey side, are Cooper's,
Newton, Timber, Manto, Clemell, and Popo, creeks.
These afford a much greater body of water to the Dela-
ware, than is afforded at any other part of the river within
the same distance.
The changes that take place in the river are a subject
of primary importance. To it, attention has been direct-
ed, from first to last. It is obvious, that these changes
are effected by the water, either directly or indirectly,
nnder the influence of its velocity and direction.
On this subject, much has been written ; and it is hum-
bly conceived that important materials are here afforded,
for the further investigation and improvement of this
31
much-neglected, though important, branch of natural phi-
losophy. It is true, that all that can be expected is to
establish general principles. To pretend to bring this
subject to so great a perfection as to be able to anticipate
precisely all the changes that will take place, would be-
tray as much presumption and ignorance as is displayed
in our almanacs, where we are informed of the state of
the weather for many months to come.
It is possible, that the freshet of one day may be pro-
ducing and carrying on certain eiFects, which a strong
wind, or body of ice, may, in a few days afterward, avert,
and produce a contrary impression.
Taking into consideration, therefore, the constant
changes of the winds, of the rise of tides, of the uncer-
tainty of freshets, of ice, and of local obstructions which
are sometimes thrown in the channel, it would be impos-
sible to foretel precisely what changes may take place.
It is well known that variations have occurred, very con-
trary to the expectations of judicious persons.
Yet, notwithstanding the subject will admit of much
profitable investigation, and although we may not be led
fully to anticipate what changes may hereafter occur, yet
we may advance so far in improvement, as to be able to
calculate, with some degree of certainty, what would take
place under certain circumstances.
Such land-marks were preserved, in the survey, as were
likely to prove serviceable in ascertaining the changes
that may result in the course of time. It would be highly
advisable, that, every few years, the changes, at least for
the most important parts of the river, be ascertained and
reported. Such inspection would not be attended with
much expense, and would be highly profitable.
Thus I have rapidly glanced over such subjects as ap-
peared to have a direct claim to my attention, in the sur-
vey of the river. Much more might be added, particu-
32
larly in such speculatiA^e inquiries as might have a prac-
tical bearing on the improvement of our navigable waters.
This, however, is reserved for more mature deliberation.
I cannot close this subject, without expressing the
various sensations experienced on meeting the remains
of those ships of war, some of which had been employed
by our enemies, during our ever memorable revolution, in
opposing our liberty and independence ; while others were
employed by our worthy forefathers, and made the ho-
noured instruments by which they asserted our rights,
and freed us from bondage.
Here lie the Augusta and Marlin, perishing in our
waters in disgrace, their memory only retained as tro-
phies of victory. There lies the memorable frigate Alli-
ance : she maintained her post, in the struggle for free-
dom, when all the rest of our ships were swallowed up in
the contest. Her decks once bore the bold, intrepid Paul
Jones, under whose command she often rode victorious.
Worn out in service, her remains now repose near the
\vestern banks of Petty 's island, now the soil of liberty
and freedom. Nor shall she lie forgotten, while the vic-
tories won are worth the recollection, or this pen lives to
record her memory.
DAVID M'CLURE.
July 4, 1820.
APPENDIX.
THE following is a list of the soundings, in feet, at
low water, at some of the most important parts of the
river, taken at right angles across from shore to shore.
They are obtained from the map, at certain equal dis-
tances apart ; so that the relative situation of each depth
is readily found, by dividing a line into one part more
than the number of soundings, and annexing to each
point of division the depth in the order exhibited in each
line.
From Richmond to Petty 's island, 10, 15, 10, 9, 18, 19,
20, 21, 20, 15, 11, 14, 12.
In the direction of Richmond, from Petty's island to
Jersey, 12, 16, 20, 24, 22, 14, "S.
From the east point of Petty's island to Jersey, 19, 38,
23, 16, 18, 10.
Across the mouth of Cooper's creek, from west to east,
1, 3, 5, 8, 5.
From the wharf at the Glass-House to Petty's island,
16, 28, 33, 32, 25, 22, 21, 14.
From the south point of Petty's island to Pennsylvania,
4, 12, 18, 25, 34, 38, 26, 12, 3.
From the south point of Petty's island to Jersey, 1, 3,
5, r, 20, 22, 21, 18, 15, 12, 11, 8, 10.
From Nagle's wliarf, at the moutli of Cohocksink
creek, to Cooper's Point, 29, 40, 34, 26, 20, 18, 18, 16,
16, 18, 19, 19, 13, 14, 11.
5
34
In the direction of Callowhill street, from Pennsylvania
to Jersey, 37, 46, 44, 33, 22, 17, 11, 6, 4— bar — 2, 8^
10, 12, 10, 6, 5.
In the direction of High street, from Pennsylvania to
Jersey, 42, 42, 37, 28, 10, 2, 1^— bar— U, 2, 5, 7, 11,
12, 12, 11, 7, 7, 7, 4.
In the direction of Walnut street, from Windmill island
to Jersey, 2, 5, 9, 11, 12, 12, 12, 9, 8, 10, 9.
From the first wharf above Pine street to the wharf on
Windmill island, 43, 44, 39, 29, 18.
From the south end of Windmill island to Pennsylvania,
12, 32, 35, 20, 19, 20.
From the south end of Windmill island to Jersey, 6,
10, 14, 16, 16, 18, 18, 18, 10.
From Kaign's Point to the piers at M'Leod's rope-
walks, 8, 18, 24, 26, 24, 14— bar— 13, 19, 27, 28, 26,24,
22, 17, 13, 10, 10.
From Jersey to Pennsylvania, at a point about half
way between Kaign's and Gloucester Points, 13, 22, 31,
£8, 32, 21, 19, 17— bar— 17, 17, 19, 22, 24, 20, 16, 12.
From the wharf at the Point to Jersey, 23, 25, 29, 33,
27, 26, 25, 23, 14, 6, 4.
From Gloucester wharf to Pennsylvania, 9, 14, 18, 24,
26, 33, 38, 31, 25, 17, 5.
From the north end of League island to the Windmill,
Jersey, 3, 4, 7, 9, 10, 12, 12, 12, 13 — shoal called the
Horse Shoe— 20, 29, 36, 30, 18, 15, 13, 9, 7, 5.
From a white house on League island, commonly called
Buttermilk Tavern, to a point two hundred yards below
Eagle Point, 6, 11, 19, 22, 23, 26, 25, 24, 25, 26, 28, 29,
29, 29, 28, 19, 10, 5, 4.
From the south end of League island to Jersey, 1, 3, 7,
12, 15, 19, 24, 24, 29, Z7 , 25, 24, 21, 18, 15, 10, 8, 1—
bar — 4, 11, 21, 19.
Across the mouth of Schuylkill, from east to west, 10,.
15, 20, 28, 30, 23, 15, 10.
35
Schuylkill brings out over the flats from 8 to 10 feet.
From Red Bank, near the Telegraph, towards the old
Lazaretto, 10, 22, 12, 2— bar — 1, 1, 2, 4, 8, 13, 16, 17,
18, 20, 26, 28, 29, 29, 28, 23, 22, 18, 10, 8, 6, 5, 4, 3, 3,
5, 2.
From the first pier below the fort, to Davis's pier, or
fort Gaines, 23, 23, 26, 29, 30, 29, 31, 27, 24, 24.
From fort Gaines to Jersey, 3, 4, 6, 9, 14, 14, 13, 11,
10, 10, 14, 19, 20, 14, 7, 3, 1.
From Boom or Diamond piers to Jersey, 42, 33, 30, 31,
29, 25, 23, 16, 8, 5— bar— 4, 5, 4, 4, 14, 13, 12, 17, 19,
20, 16, 10, 7, 0— bar— 0, 2, 1, 1.
From a point near the middle of Hog island to Jersey,
9, 18, 23, 28, 28, 26, 24, 17, 11, 8, 12, 14, 31, 29, 16, 14,
11, 13, 12, 9, 9, 7, 6, 4, 3.
From the south point of Hog island to Jersey, 6, 7, 8,
12, 15, 15, 11, 11, 9, 6, 4— bar — 4, 14, 19, 24, 28, 33, 30,
28, 27, 21, 23, 24, 24, 22.
From the north point of Maiden island to Billingsport
wharf, Jersey, 2, 6, 7, 9, 13, 23, 30, 34, 30, 28, 26, 23,
22, 21, 18, 10.
From the north point of Maiden island to Martin's bar,
2, 8, 11, 13, 12, 15, 16, 7.
From the north point of Tinnicum island to Pennsyl-
^ vania, 1, 3, 7, 12, 12, 14, 12, 10, 9, 9, 9, 10, 11, 13, 12.
From the north Point of Tinnicum island to Jersey, 9,
18, 28, 29, 32, 37, 37, 40, 42, 41, 35, 18, 6.
From the mouth of Clemell creek to Tinnicum island,
3, 6, 10, 16, 18, 20, 29, 29, 30, 30, 29, 29, 21, 20, 15, 9.
From the wharf at Thompson's Point to Tinnicum
island, 5, 8, 14, 20, 20, 23, 26, 29, 29, 29, 30, 31, 31,
28, 17.
From the north end of Monnis's island to Jersey, 1, 2,
4, 5, 4, 3.
From the south end of Tinnicum inland to Jersey, 4,
14, 20, 24, 28, 29, 28, 26, 26, 24, 22, 18, 19, 17, 9,
36
From the Lazaretto wharf to Tinnicum island, 20, 11,
—a shoal— 16, 16, 14, 17, 18, 19, 20, 21, 22, 23, 19, 15,
13, 8.
From the south point of Tinnicum island to Pennsyl-
vania, 11, 23, 26, 25, 25, 22, 19, 11.
From the north end of Chester island to Jersey, 6, 15,
20, 18, 9, 2.
From the north end of Chester island to Pennsylvania,
1, 4, 10, 19, 26, 30, 33, 18 — lower end of the bar from
Tinnicum— 24, 26, 20, 10, 5.
From the south point of Chester island to Jersey, 10,
17, 20, 19, 15, IS, 10, 9, 6.
From the north wharf at Chester to the south point of
Chester island, 20, 21, 25, 27, 29, 31, 31, 31, 28, 25, 23,
21, 19, 18, 15, 12, 4, 4, 3, 7, 10, 7, 8.
From Pennsylvania to Jersey, half way between Ches-
ter and Schiver's island, 8, 19, 23, 28, 29, 22, 17, 12, 13,
16, 14, 8, 13, 13, 15, 17, 10, 4, 1.
From the north point of Schiver's island to Jersey, 4,
5, 6, 5, 4.
From the north point of Schiver's island to Pennsylva-
nia, 18, 20, 20, 20, 22, 23, 24, 26, 28, 30, 30, 27, 23, 20,
15, 11.
Across the bar, below fort Mifflin, there is, in the deep-
est part of the channel, about 12 feet. The channel is
narrow, and liable to many changes.
The following are the soundings, taken at low vt^ater,
on the 29th of July, 1820, four days after the full moon,
at the end of all the principal wharves in Philadelphia,
beginning at Kensington, and descending the river.
feet.
feeu
1 Seguin's wharf.
16
5 Warder's wharf,
19
2 Saxton's do.
16
6 Walter's do.
19
3 Nagle's do.
16
7 Bubble's do.
13
4 Stiles's do.
16
8 Hains's do.
6
37
feet.
9 Randolph's wharf, 25
10 Bi'ittoii's do. 26
11 Callowhill St. do. 28
12 Katz's do. 30
13 West's do. 30
14 Vine St. upper do. 19
15 Flintham's do. do. 30
16 Flintham's lower do. 12
17 Smith's wharf, 36
18 Race St. do. 42
19 Warder's do. 37
20 Pratt's do. 19
21 Hodge's do. 22
22 Smith's do. 20
23 Sumerl's do. 25
24 Arch St. wood do. 40
25 Perot's wliarf, 20
26 Girard's do. 42
27 Fish Market do. 22
28 Market St. do. low-
er side, 20
29 Chestnut St. wood
wharf, 36
30 Chestnut St. wharf,
lower side, 12
31 Gardner's wharf, 20
32 Walnut St. upper and
lower side, 6
33 Ross's wharf, 20
34 Morton's do. 18
5,5 Morris's do. 20
36 Hamilton's do. 20
37 Drawbridge wood
wharf, 26
38 Wall's wharf, 22
feet.
39 Spruce St. do.
R. Wain's, 19
40 Sims's wharf, 31
41 Pine St. wharf, 7
42 Willing & Francis'
upper wharf, 25
43 Willing & Francis'
lower wharf, 15
44 Guthbert's wharf, 14
45 Clapier's do. 15
46 W. Wain's do. 32
47 Penrose's do. 27
48 Almond St. wood
wharf, 20
49 Ogleby's wharf, 18
50 Huddle's do. 8
51 Alberson's do. 14
52 Catherine St. do. 20
53 Queen St. do. up-
per side, 18
54 Queen St. do. low-
er side, 12
55 Christian St. wh. 17
5Q Delevau's do. 15
57 Ware's do. 15
58 Berton's do. 15
59 Humphreys' do. 14
60 Prime St. do. 6
61 Navy yard do. up-
per side 14
62 Navy yard do.
lower side, 1 1
The end of Smith's wharf,
on the island, is at the
low water mark.
38
The wharf, nearly oppo- above tlie low water
site Pine St. on the mark.
island, is 10 feet above The lower wharf, on the
the low water mark. island, is 12 feet abore
Humphreys' wharf, on the low water mark.
the island, is 15 feet
The wharves from Callowliill street to Chestnut street
have the deepest water. This may be accounted for, from
the circumstance, that the water, descending the channel
east of Petty's island, spends its whole force against the
wharves in that vicinity. Shortly after the water leaves
Chestnut street wharf, it takes a direction over towards
the south end of Windmill island, leaving the wharves in
South wark considerably to the west of the bed of the river,
and consequently in shoaler water.
The bar, opposite Philadelphia, and at the north end
of Windmill island, has undergone one of the greatest
changes, during the last year, that was ever known. On
the l6th of January last, a storm from the east broke up
the icy fetters in the river. On the 17th, the wind blew
strong from the southward j and the tide rose higher than
it had done for a considerable time previous, inundated
many of the wharves, and covered them with drifting ice.
Shortly after tlie flood had set in, a large body of ice was
collected on the bar, nearly opposite Arch street, to the
height of nearly twenty feet, in the short period of about
ten or fifteen minutes, and continued there a number of
days. There can be no doubt that this bed of ice was
instrumental, in connexion with the drifting ice, in pro-
ducing the great change that followed.
The wreck lying on the east side of the island, last
year, was on a line with the soutli edge of the wharf;
since which, it has been removed in a line with the north
39
^dge of the wharf. It is highly prohable that this change
of position has promoted the change of the bar in that
vicinity.
The bar, a short time since, was surveyed, in order to
ascertain the precise change that has taken place since
last year. The draught in the Plate, at A, represents the
state of the bar, on the 4th of October, 1819 j and at B,
its state agreeably to the recent survey, taken on the £Oth
of July, 1820. From the inspection of these, it will be
obvious that the channel of last year is now converted into
a bar, and the bars of last year into channels.
On the ebb tide, particularly towards the close, the tide
runs with considerable strength across the bar towards
the Jersey shore. This was also found to be tlie case on
the bar north of Davis's pier, opposite fort Mifflin.
Description of the machine by which the rise and fall of
the tide were ascertained.
Let A be an upright post, to be
driven firmly into the ground, in
a suitable depth of water ^
B, the lower float board ;
C, the upper float board ;
n, the springs.
As the tide rises, the float board
C will also rise, and the springs
n n continue to pass over the
notches, until the water has at-
tained its height j at w hich posi-
tion the float board C will remain,
being prevented from falling with
the tide by the springs n n.
B-
B
-^
^\
'av
\0V
40
In like manner, the float board B will continue to de-
scend until low water, where it will be retained Uy the
springs nn on the top of it, and prevented from rising
with the tide.
A rod, as at D, duly marked, and passed through a
hole from the upper float board, so as to rest nn the lower
float board, will designate the height of the tide above
low water.
If this machine be left in the water, it will exhibit the
highest and lowest tide during the year, or for any length
of time.
Description of the Plotting Table.
This instrument is similar to the common draft board,
both as regards its frame, and the plan of fixing the pa-
per for drawing. It may be made either square or ob-
long, and of any size, to suit the extent of the draught,
and the degree of accuracy required. Round the frame,
(Fig. 3) are graduated the degrees and quarters of a cir-
cle whose centre is in the middle of the instrument. A
strip of narrow paper may be glued round the frame, to
receive the marks of the degrees and quarters. But strips
of brass or box-wood, let into the frame, for the gradu-
ated degrees, would be much more durable, though they
are not so easily marked. This instrument may be made
portable, by placing hinges on the two upper sides of the
opposite corners, and on the inside of the remaining cor-
ners of the frame ; and having the board for the paper
composed of pieces.
In proceeding with the application, the instrument will
be sufficiently explained.
To draw a line parallel to a given line. (Fig. 4.) Let
tt 6 be a given line, to which it is required to draw an-
other, parallel thereto. Lay tlie edge of the rule m on
41
the line a &, and at the same time press the piece n against
the side B D. Move the rule m, and the piece n, in that
position, and it will give the parallel direction for any line
towards C and D. If the parallel he required towards A,
let the piece n be placed against A C, while the edge of
the rule m covers the line a h : then move the rule, as
before, for the parallel position of any line towards A.
Hence it is obvious, that the instrument will answer the
purpose of an accurate parallel rule.
To draw lines at right angles. (Fig. 5.) Press n against
B D, and at the same time let the edge of the rule m cut
90 on B D and A C. Draw one of the lines in that posi-
tion, or in any other, by moving the rule as a b. Place
n against C D, and at the same time let the edge of the
rule cut 0 on A B and C D. Draw the other line in that
or any other position as c d, and it will be at right angles
to the former line.
To draw any angle. (Fig. 6.) Suppose 32 degrees be
required. Place the rule in 0 on A B and C D, and draw
a line there, or in any parallel position, as a h. Let the
rule m be placed at 32 in A B, and at 32 in C D, the
edge of which will be 32 degrees, with the former line
drawn from 0 to 0, making the angular point in the cen-
tre, from which the degrees are all drawn. If the angle
is to be made in another place, as with the line a &, move
the rule in that parallel position. If a 6 be near D, the
piece n must be against C D ; but if a 6 be near the
corner A, the piece n must be against A B, the reason of
which is obvious. To draw any other angle, in any part
of the table, will be readily understood from this example.
From these three problems, it is evident that all the
cases of trigonometry may be readily projected and re^
solved.
-6
42
To plot a survey. (Fig. 3.) For example
ch. lin ks.
1.
N. 50° E.
9
60
2.
S. 32° E.
16
38
3.
S. 41° W.
6
30
4.
West
8
43
5.
N. 79° W.
10
92
6.
N. 5° E.
11
25
7.
S. 83° E.
6
48
It is scarcely necessary to say, that a line drawn from
0 on A B to 0 on C D, or any parallel to the same, will
represent a meridian ; tliat a line from 90 on B D to 90 on
A C, will represent the east and west line ; that the top
represents the north, the bottom the south, the right the
east, and the left the west.
The point of the first station may be assumed anywhere
on the paper, so that, on protracting the field, there may
not be a side thrown beyond the paper, in some of the
subsequent courses. Let A be the point from which the
field is protracted. Let the edge of the rule m be placed
on 50 near the corner B, and 50 near the corner C ; the
piece n, at the same time, against the side A C Move
the rule to the suitable position A, the assumed point, and
draw the line A B, on which set off, from any scale of
equal parts, 9.60. Place the edge of the rule m on 32 in
A B, nearer the corner A, and 32 in C D nearer D. The
piece w, at the same time against A B. Move the rule,
until the edge thereof is in the point B ; and draw B C
equal to 16.38. Let the edge of the rule be placed in 41
near C, and 41 near B ; the piece n against C D. Bring
the edge of the rule to the point C, and draw C D equal
to 6.30. Again, let the edge of the rule be put on 90 in
B D and A C, and the piece n either against A C or B D.
Bring the edge of the rule to the point D, and draw D E
equal to 8.43. In like manner proceed with the sides E F,
F G, and G A.
43
To ascertain the contents of a survey. (Fig. 3.) For
example, the field just protracted. The whole principle
consists in throwing the figure into a triangle, which this
instrument is capable of doing with great facility and
accuracy.
Assume any side for a hase line, which, when produced,
shall not fall within any part of the figure, as A B neces-
sarily would. Take B C, which produce indefinitely to-
wards X and y. Lay the edge of the rule m on the point
B and G, and the piece n against the side A C. Move
the rule in that position to the point A; mark the point of
intersection of the edge of the rule, and the base line B C
in a. Place the edge of the rule in F and a, and move
the rule in that position to the point G. Mark the point
6, and place a circle round it for distinction, as the apex
F is now arrived at a point whose distance is the greatest
from the hase line. So also proceed to reduce the parallel
position of the points C and E to D, and mark on the
base line the point of intersection d; and, with the paral-
lel position F and d!, reduce E to e. Tlien will the field
be reduced to the triangle ¥ h e. The length of the base
e b being ascertained by the compasses, and multiplied by
half the perpendicular, will give the area.
The demonstration of whicli is as follows. The triangle
a A G is equal to the triangle A B «, being constituted
on the same base A a, and between the parallel lines A a
and G B. So also the triangle 6 F a is equal to the tri-
angle G F a, being constituted on the same base F a, and
between the parallel lines G 6 and F a. Therefore the
triangle F 6 a is equal to the figure F G A B a F. In like
manner may the triangle F e C be proved to be equal to the
figure C D E F C And consequently the triangle 6 F e
is equal to the whole figure A B C D E F G A. In as-
suming a side for the base, it is best to take that side
which would throw the survey in a triangle nearest the
equilateral form. The base of this triangle was found to
44
be 26 chains 8 links ; and the perpendicular, 21 chains 35
links ; from which the area was found to be 28 acres, 2
roods, 1.744 perches ; — by calculation, 28 acres, 2 roods,,
2 perches, differing about one-fourth of a perch.
The size of the instrument by which the river was pro-
jected, was nearly three feet square ; and so constructed
as to admit the paper (which, when prepared for the map,
was nearly thirteen feet long) to be drawn forward as the
draughting progressed.
On the utility and superiority of this invention, I deem
it unnecessary to make any remarks.
MY grateful acknowledgments are due to those gentle-
men who kindly promoted the interest of the different
experiments made on the river, and for the assistance
which they so cheerfully afforded on that occasion.
A report having been industriously circulated, last win-
ter, that gross inaccuracies existed in the soundings of
that part of my survey between Windmill island and the
Jersey, and near the site of a certain contemplated bridge,
I feel it a duty to myself and the public, to testify against
such misrepresentations. To satisfy the public, to whom
I am accountable for the faithful discharge of a public
trust, I present for their perusal the following certificates,
which first show that I was duly qualified for the work
which I was called to perform ; and secondly, that I have
been faithful, and am correct in that part of my survey
which has been shamefully contradicted, by certain per-
sons, excited by interested motives.
David M'Clure, Esq. of this city, has shown to me a
draught and description of his survey of the river Dela-
ware. He has also explained the method used by him to
45
take the soundings, and to describe the shores, islands,
flats, and bars in the river. All which appear to have
been performed upon strict geometrical principles, in such
way as ought to ensure accuracy in the work.
Samuei. Hains,
City Surveijor.
Philad. Jaiu 8, 1820.
I have also heard from Mr. M'Clure an explanation of
the methods adopted in making the survey of the river
Delaware, and concur with Mr. Hains in the opinion ex-
pressed above.
R. M. Pattersokt,
Professor oj Mathematics in the Univ. of Penn.
I also have examined Mr. M'Clure's draught ; and,
although I do not profess to be versed in such matters, am
inclined to think it has been executed with diligence and
success, and may be rendered useful.
Frederick Beasiey,
Provost of the Univ. of Penn.
The following is from Captain James Josiah, master
warden, and Joseph S. Lewis, Esq.
Philad. Feb. 15, 1820.
Some doubts having been suggested, respecting the
accuracy of Mr. M'Clure's survey of the river Delaware,
the subscribers this day proceeded to sound the river, from
"Windmill island towards Camden, on a line, as nearly
as they could ascertain it, of the contemplated bridge.
46
The ice on the east end of the island was standing; and
they took a boat, and passed over it, commencing sound-
ing about one hundred feet from the east side of the island,
and found, at about every hundred feet, the following
soundings, — the tide being about an ordinary high water:
8, 9, Hi, 15i, 17, 17i, 18, 17i, 17i, 17, 14i, 12, Hi, 12i,
Hi.
James Josiah,
Joseph S. Lewis.
The above soundings, being reduced to low water, by
allowing the ordinary rise of five feet, will give six inches
more than that exhibited in my chart.
"We, the subscribers, do certify, that, on the 3d of Au-
gust, 1820, we accompanied David M'Clure, Esq. on an
examination of the channel between Windmill island and
the Jersey, at low water ; that we had the satisfaction, on
sounding the said channel, to compare the same with the
original draught, which was before us ; and can declare,
that we are fully of the conviction, that it is substantially
correct, and corresponds to the low water mark at which
it was taken.
We found, throughout the whole channel, in its various
parts, uniformly one foot more than is exhibited in Mr.
M'Clure's chart, owing, as may be inferred, to the low
water being one foot higher than it was at the time the
soundings were taken for the chart.
We found, throughout the channel, a deptli of thirteen
feet, the narrowest part of which, as near as could be es-
timated, was four hundred and fifty feet, commanding a
a depth of eleven feet.
47
To prevent any mistakes, the line by which the sound-
ings were taken, was carefully measured, before we com-
menced the inspection.
Francis Troubat,
William G. Whyte,
James West,
William Tremper,
William E. Tucker.
Report of the Committeef on the subject of the Survey of
the River Delaware.
The Committee appointed by the Select and Common
Councils, to have a survey of the river Delaware made,
from Petty's island to one mile south of Chester, beg
leave to report to Councils, that they proceeded in the
execution of the trust (Committed to them, by employing
Mr. David M'Clure as surveyor, and competent hands as
assistants, who commenced the survey on the 26th day of
June last, and finished the same on the 9th day of October
last ; that the surveyor has made a Report, and a drauglit
of the survey, which the Committee believe is entirely
accurate, and which they herewith submit to Councils as
part of their Report. All which is respectfully submitted-
Joseph S. Lewis,
J. W. Thompson,
Stephen Girard,
John M'Clintock.
Fhiladelphia, February 10, 1820.
INDEX.
An account of the changes that have taken place in the river
Delaware, - ..... 5
Some remarks upon the inside channels, ... 6
Some account of the bar below Fort Mifflin, and of Davis's Pier,
or Fort Gaines, ....... 7
Remarks on the manner in which sediment is collected, and
shoal water produced, -8
General observations on the current, - - - - - 8
Remarks on the banks of Hog Island, - - ... 9
An account of the channel east of Windmill island, - - 10
The highest and lowest tides, when produced, - - - 12
The rise and fall of the tide, for every half hour, - - - 12
The effects of a freshet, - - - - - 14
General remarks on the theory of the tides, - - - 14
Tides supposed to ascend above their level, - - - 15
The distance floating matter is carried down by the current, at
the close of the ebb and flood, - - - - - 17
Remarks on the fall of the tide, towards the close of the flood, 18
An experiment to find whether the surface or bottom of the
river has the greater velocity, - - - - - 19
An experiment to find the different velocities, from the surface
to the bottom, ...... 19
Tables exhibiting the different rates of the current, for every
half hour, with the different velocities, from top to bottom, 24
A calculation for the quantity of upper water brought down the
river every twelve hours, - ----- 27
Remarks on the different velocities of the current, - - 27
Different vertical sections of the river, . - ... 28
Remarks on the changes of the river, . .... SO
The soundings for the most remarkable places, - - - 33
Depth of water at the end of the principal wharves at Philad. 36
An account of the bar, opposite the city, - - - 38
Description of the tide machine, ...... 39
Description of the Plotting Table, - . . . . 40
Certificates, - ..... 44
Report of the Committee to Councils, - - - - 47
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Deacidlfied using the Bookkeeper process.
Neutralizing Agent: IVIagnesium Oxide
Treatment Date:
JUH 1993
BKKEEPER
PRESERVATION TECHNOLOGIES, L.P.
m Thomson Park Drive
Cranberry Township, PA 16066
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